LXR busybox/procps/watch.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini watch implementation for busybox
   4 *
   5 * Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
   6 * Copyrigjt (C) Mar 16, 2003 Manuel Novoa III   (mjn3@codepoet.org)
   7 *
   8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9 */
  10//config:config WATCH
  11//config:       bool "watch (4.4 kb)"
  12//config:       default y
  13//config:       help
  14//config:       watch is used to execute a program periodically, showing
  15//config:       output to the screen.
  16
  17//applet:IF_WATCH(APPLET(watch, BB_DIR_BIN, BB_SUID_DROP))
  18
  19//kbuild:lib-$(CONFIG_WATCH) += watch.o
  20
  21//usage:#define watch_trivial_usage
  22//usage:       "[-n SEC] [-t] PROG ARGS"
  23//usage:#define watch_full_usage "\n\n"
  24//usage:       "Run PROG periodically\n"
  25//usage:     "\n        -n      Loop period in seconds (default 2)"
  26//usage:     "\n        -t      Don't print header"
  27//usage:
  28//usage:#define watch_example_usage
  29//usage:       "$ watch date\n"
  30//usage:       "Mon Dec 17 10:31:40 GMT 2000\n"
  31//usage:       "Mon Dec 17 10:31:42 GMT 2000\n"
  32//usage:       "Mon Dec 17 10:31:44 GMT 2000"
  33
  34/* BB_AUDIT SUSv3 N/A */
  35/* BB_AUDIT GNU defects -- only option -n is supported. */
  36
  37#include "libbb.h"
  38
  39#define ESC "\033"
  40
  41// procps 2.0.18:
  42// watch [-d] [-n seconds]
  43//   [--differences[=cumulative]] [--interval=seconds] command
  44//
  45// procps-3.2.3:
  46// watch [-dt] [-n seconds]
  47//   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
  48//
  49// (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
  50
  51int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  52int watch_main(int argc UNUSED_PARAM, char **argv)
  53{
  54        unsigned opt;
  55        unsigned period = 2;
  56        unsigned width, new_width;
  57        char *header;
  58        char *cmd;
  59
  60#if 0 // maybe ENABLE_DESKTOP?
  61        // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
  62        close(STDIN_FILENO);
  63        xopen("/dev/null", O_RDONLY);
  64#endif
  65
  66        // "+": stop at first non-option (procps 3.x only); -n NUM
  67        // at least one param
  68        opt = getopt32(argv, "^+" "dtn:+" "\0" "-1", &period);
  69        argv += optind;
  70
  71        // watch from both procps 2.x and 3.x does concatenation. Example:
  72        // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
  73        cmd = *argv;
  74        while (*++argv)
  75                cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
  76
  77        width = (unsigned)-1; // make sure first time new_width != width
  78        header = NULL;
  79        while (1) {
  80                /* home; clear to the end of screen */
  81                printf(ESC"[H" ESC"[J");
  82                if (!(opt & 0x2)) { // no -t
  83                        const unsigned time_len = sizeof("1234-67-90 23:56:89");
  84
  85                        // STDERR_FILENO is procps3 compat:
  86                        // "watch ls 2>/dev/null" does not detect tty size
  87                        new_width = get_terminal_width(STDERR_FILENO);
  88                        if (new_width != width) {
  89                                width = new_width;
  90                                free(header);
  91                                header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
  92                        }
  93                        if (time_len < width) {
  94                                strftime_YYYYMMDDHHMMSS(
  95                                        header + width - time_len,
  96                                        time_len,
  97                                        /*time_t*:*/ NULL
  98                                );
  99                        }
 100
 101                        // compat: empty line between header and cmd output
 102                        printf("%s\n\n", header);
 103                }
 104                fflush_all();
 105                // TODO: 'real' watch pipes cmd's output to itself
 106                // and does not allow it to overflow the screen
 107                // (taking into account linewrap!)
 108                system(cmd);
 109                sleep(period);
 110        }
 111        return 0; // gcc thinks we can reach this :)
 112}
 113